Feculent and fetid (foetid)

Feculent is an adjective that is sometimes misused.

It refers to fluid that is contaminated; filthy, muddy, scummy and foul … extending in some contexts to having excrement or faeces within it.

Fetid (also spelt as foetid) is particular in its meaning. It applies to something that is foul-smelling; offensively stale and nauseating.